Danaus plexippus

Family Description:
Idaho's State Insect:
The Monarch Butterfly (Danaus plexippus) was adopted as the state insect by the state legislature in 1992.

Caterpillar: The caterpillar is very colorful and eye-catching. It is striped vertically with black, white, and yellow, and has two long filaments in front and two shorter filaments on the rear.
Adult: The butterfly is large, with a wingspan of 3 to 4 inches. The upperside is bright orange and marked with black, both along the wing borders and the wing veins. The outer wing border is dotted with white. The outermost tip of the forewing is spotted with orange and white. The hindwing is marked with black veins only, and is lacking the continuous curved black line present on Viceroys. Underneath is paler orange but similarly marked.

This species is found throughout North America, from the southern two-thirds of Canada south through the U.S., Mexico, Central and South America. It also occurs in Australia, Hawaii, and other islands of the Pacific. In Idaho, it occurs through most of the state.

Habitats include a variety of open places, including meadows, fields, and valley bottoms.


Caterpillar: Caterpillars feed on the leaves and flowers of milkweeds (Asclepius spp.) and dogbane (Apocynum spp.).
Adult: Butterflies drink flower nectar from milkweeds, members of the sunflower family (Asteraceae), and other flowers.

A great deal is known about the biology of Monarchs. In most of its range in North America, there can be several generations each summer, and as many as six in the south. Certain populations, in Florida, southern Texas, and southeastern California, may breed all year. Monarchs in temperate locations migrate thousands of miles to overwintering sites located primarily in California and Mexico, or along the Gulf or Atlantic coasts. The migrating butterflies roost in trees as night, and may form huge groups in trees at overwintering sites. In spring, the butterflies head back up north, mating before or along the journey. Females lay eggs on the way, and it is the offspring which complete the journey.

Monarch caterpillars and butterflies are distasteful to most predators, due to compounds retained in the body obtained from feeding on milkweeds. Potential predators learn to avoid the brightly colored caterpillars and adults; other "tasty" butterfly species, such as the Viceroy, have come to appear similarly to take advantage of the Monarch’s warning coloring.

Males actively patrol in search of receptive females. Females lay eggs singly on the undersides of host plant leaves, and sometimes on the stems or flowers.

Idaho Status: Unprotected nongame species.
Global Rank: G5
populations are widespread, abundant, and secure. Some critical overwintering sites in California and Mexico require protection to ensure the continued abundance of the species in our area.

Ferris, C. D. and F. M. Brown. (eds.) 1981. Butterflies of the Rocky Mountain States. Univ. of Oklahoma Press, Norman, Oklahoma, USA, 442 pp.

Opler, P. A., H. Pavulaan, and R. E. Stanford. 1995. Butterflies of North America. Jamestown, North Dakota, USA: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/distr/lepid/bflyusa/bflyusa.htm (Version 05Nov98).

Opler, P. A. and A. B.Wright. 1999. A Field Guide to the Western Butterflies.    Second Edition.  Peterson Field Guide Series. Houghton Mifflin Company, New York, New York, USA, 540 pp.

Pyle, R. M. 1981. National Audubon Society Field Guide to North American Butterflies. Alfred A. Knopf, Inc., New York, New York, USA, 924 pp.

Scott, J. A. 1986. The Butterflies of North America. Stanford University Press, Stanford, California, USA, 583 pp.

Stanford, R. E. and P. A. Opler. 1993. Atlas of Western U.S.A. Butterflies (Including Adjacent Parts of Canada and Mexico). Published by authors, Denver, Colorado, USA, 275 pp.